Previous research has demonstrated that employee and leader mindfulness play a significant role for well-being at work. Yet, we lack a sufficient understanding of how leader mindfulness translates into subordinates’ well-being. In this paper, we argue that transformational leadership serves as a mediating mechanism of the relationship between leader mindfulness and subordinates' well-being (i.e., positive and negative affect, job satisfaction, psychosomatic complaints, and emotional exhaustion) at work. Findings are reported from a cross-sectional multi-source study with 65 leaders and 153 employees from different industries. Multilevel mediation analyses showed that leader mindfulness was positively related to subordinates’ positive affect as well as job satisfaction and negatively related to subordinates’ psychosomatic complaints via transformational leadership. This study adds to the literature on mindfulness at work in underlining the importance of leader mindfulness for subordinates’ well-being introducing transformational leadership as a mediating variable. We discuss the importance of reconciling research on mindfulness and leadership, and of promoting mindfulness in organizations.